Pen



FIG. 1 is a perspective view of a pen;

FIG. 2 is a side view thereof;

FIG. 3 is a front view thereof;

FIG. 4 is an opposite side view to that shown in FIG. 2;

FIG. 5 is a rear view thereof;

FIG. 6 is a bottom view thereof; and,

FIG. 7 is a top view thereof. 

The ornamental design for a pen, as shown and described. 